Content for TS 23.161 Word version: 18.0.0

1… 5… 6… 6.2… 6.2.4 6.3… 6.3.2.2… 6.3.3… 6.3.3.2… 6.4… 6.4.2.2… 6.5… 6.5.2… 6.5.3… 6.6… 6.6.1.3… 6.6.2… 6.7… 6.7.2… 6.8…

6.8 Network-initiated release of NBIFOM PDN connection 6.8.1 General 6.8.2 PDN GW initiated procedures

6.8 Network-initiated release of NBIFOM PDN connection p. 64

6.8.1 General p. 64

The Network-initiated release of NBIFOM PDN connection procedure may be triggered by SIPTO, as defined in TS 23.401. In this case, the PDN GW initiates Bearer Deactivation procedure upon receiving a Release Over Any Access indication from the MME.

The Network-initiated release of NBIFOM PDN connection procedure may also be triggered due to P-CSCF Restoration, as defined in TS 23.380. In this case,

The PDN GW initiates Bearer Deactivation procedure as described in clause 6.8.2 upon receiving a P-CSCF Restoration indication from the PCRF, the 3GPP AAA server, or the MME/SGSN, or
The PDN GW initiates Bearer Deactivation procedure in WLAN upon receiving the Release Over Any Access indication from the MME/SGSN as described in clause 6.8.2.
- The MME sends the Release Over Any Access indication during the MME requested PDN disconnection procedure or MME-initiated Detach procedure upon receiving a P-CSCF Restoration indication from the HSS. Or,
- The SGSN sends the Release Over Any Access indication during the SGSN Initiated PDN connection Deactivation Procedure using S4 upon receiving a P-CSCF Restoration indication from the HSS.

6.8.2 PDN GW initiated procedures p. 65

6.8.2.1 PDN GW initiated bearer deactivation procedure p. 65

The PDN GW initiated bearer deactivation procedure defined in clause 5.4.4.1 of TS 23.401 shall be used with the following exceptions:

Step 2:
If the PDN GW has received a P-CSCF restoration indication from the PCRF, the 3GPP AAA server, or the MME/SGSN, it shall select one access supporting the basic mechanism, based e.g. on whether the access supports the basic P-CSCF restoration mechanism defined in TS 23.380. If the PDN GW has selected the 3GPP access, it shall include the Reactivation Requested indication in the Delete Bearer Request to the MME. If the PDN GW has selected the WLAN access, it shall include the cause "local release" in the Delete Bearer Request to the MME.
Steps 4 to 7 are not performed if the Cause in the Delete Bearer Request message is "local release".

6.8.2.2 PDN GW initiated Resource Allocation Deactivation with GTP on S2b procedure p. 65

For untrusted WLAN, the PDN GW initiated Resource Allocation Deactivation with GTP on S2b procedure defined in clause 7.9.2 of TS 23.402 shall be used with the following modifications:

Step 2 applies with the following addition:
- If the PDN GW has received a P-CSCF restoration indication from the PCRF, the 3GPP AAA server, or the MME/SGSN, it shall select one access supporting the basic mechanism as defined in TS 23.380. If the PDN GW has selected the untrusted WLAN access, it shall include the Reactivation Requested indication in the Delete Bearer Request to the ePDG. If the PDN GW has selected the 3GPP access, it shall include the cause "local release" in the Delete Bearer Request to the ePDG.
- If this procedure is triggered by a Release Over Any Access indication from the MME, the PDN GW shall include the cause "local release" in the Delete Bearer Request to the ePDG.
Step 3 is modified as follows: The IKEv2 tunnel release is triggered from the ePDG to the UE if all bearers belonging to the PDN connection are released and if the Cause in the Delete Bearer Request message is different from "local release". If the Delete Bearer Request message contains the Reactivation Requested indication, the ePDG includes the cause "Reactivation Requested" in the IKEv2 message to the UE.

6.8.2.3 PDN GW initiated Resource Allocation Deactivation in WLAN on GTP S2a procedure p. 65

For trusted WLAN, the PDN GW initiated Resource Allocation Deactivation in WLAN on GTP S2a procedure defined in clause 16.4.1 of TS 23.402 shall be used with the following modifications:

Step 2 applies with the following addition:
- If the PDN GW has received a P-CSCF restoration indication from the PCRF, the 3GPP AAA server, or the MME/SGSN, it shall select one access supporting the basic mechanism as defined in TS 23.380. If the IMS PDN connection is established on both accesses with the single connection mode over the trusted WLAN, the PGW shall select the 3GPP access. Otherwise,
  - If the PDN GW has selected the trusted WLAN access, it shall include the Reactivation Requested indication in the Delete Bearer Request to the TWAN;
  - If the PDN GW has selected the 3GPP access, it shall include the cause "local release" in the Delete Bearer Request to the TWAN.
- If this procedure is triggered by a Release Over Any Access indication from the MME, the PDN GW shall include the cause "local release" in the Delete Bearer Request to the TWAN.
Step 3 is modified as follows:
In multi-connection mode, if all bearers belonging to a PDN connection are released and if the Cause in the Delete Bearer Request message is different from "local release", then the UE is informed of the PDN connection release by means of a WLCP PDN Disconnection Request (PDN Connection ID). If the Delete Bearer Request message contains the Reactivation Requested indication, the TWAN includes the cause "Reactivation Requested" to the WLCP PDN Disconnection Request message to the UE.

6.8.2.4 PDN GW initiated Bearer Deactivation Procedure using S4 p. 66

The PDN GW initiated bearer deactivation procedure using S4 defined in clause 9.2.4.3A of TS 23.060 shall be used with the following additions:

Step A:
If the PDN GW receives a P-CSCF Restoration indication from the PCRF, the 3GPP AAA server, or the MME/SGSN, it shall select one access supporting the basic mechanism as defined in TS 23.380. If the PDN GW has selected the 3GPP access, it shall include the Reactivation Requested indication in the Delete Bearer Request to the SGSN. If the PDN GW has selected the WLAN access, it shall include the cause "local release" in the Delete Bearer Request to the SGSN.
In addition, if the Cause in the Delete Bearer Request message is "local release", the message Deactivate PDP Context Request in step 2 of Figure 77 in clause 9.2.4.3 is not sent to the UE.